Influence of microsilica and polypropylene fibers on the fresh and mechanical properties of ultra-high performance geopolymer concrete (UHP-GPC)

The goal of this research is to identify the impact of microsilica and polypropylene fibers (PF) on the mechanical characteristics of an ultra-high performance geopolymer concrete (UHP-GPC). The workability, compressive strength, modulus of elasticity, and splitting tensile strength of a total of 20 concrete mixtures were evaluated experimentally. To produce the mixtures, PF was utilized at four different volume fractions: 0 %, 0.75 %, 1.75 %, and 2.75 %. Moreover, five microsilica levels were employed in terms of the total mass of the binder: 0 %, 7.5 %, 15 %, 25 %, and 35 %. The findings showed that when 15 % microsilica was added to UHP-GPC, the mechanical characteristics were significantly degraded, but then enhanced when more than 15 % microsilica was added. Furthermore, PF contributes significantly to the mechanical characteristics of UHP-GPC and introducing 2.75 % PF minimizes a significant drop in the characteristics of UHP-GPC when 15 % microsilica is employed. ‎